This invention is related to elecrical power transmission systems with a broken conductor guard as set forth in my U.S. Pat. No. 4,616,287 issued Oct. 7, 1986, and is particularly directed to an improved broken conductor guard attachment system for electrical power distribution systems.
Electrical power reaches a consumer through two systems. The first system coupled power from a generating facility to and between substations and is referred to as a "transmission" system. Transmission systems are characterized by always using 3-phase lines, each line being of the same size, same length and balanced, regardless of the current magnitude carried by each phase.
The second system is a power "distribution" system in which distribution lines carry power from substations to users. While three phases are available from substations, loads are generally placed on the distribution lines in the form of single phase transformers and single phase taps to particular users. Transmission lines generally carry current at several thousands of volts while distribution lines may carry current at a few hundreds of volts.
Because transmission lines are at such high potentials, it is necessary to physically space the conductors of the lines widely apart in order to prevent conductor-to-conductor arcing. Applicant's aforementioned U.S. Patent describes a support arrangement for a broken conductor guard particularly adapted for transmission lines and for higher voltage distribution systems of more than one phase. Such systems require a relatively long guard and, in order to stablize such a guard, it was found necessary to attach the guard to two parallel, spaced neutral conductors. For distribution lines supplying relatively low voltage to residential users or small businesses, it is not believed economically practical to use a dual neutral conductor support arrangement for a broken conductor guard. However, even though a shorter broken conductor guard may be used for distribution systems, a guard attached to a single neutral conductor is inherently unstable and may oscillate or rotate to non-useful positions.
It is an object of the present invention to provide a broken conductor guard system for use with relatively low voltage power distribution systems. The present invention, in an illustrated embodiment, provides a clamping mechanism for attaching and supporting a broken conductor guard on a single neutral conductor such that the guard is maintained substantially in a horizontal plane below a power carrying conductor. In one form, in which the distribution system has at least one power conductor suspended between power poles with a neutral conductor suspended vertically below the power conductor, the guard comprises an elongated rod having hook-shaped ends and is supported from the neutral conductor by a clamp which holds the guard in a horizontal plane and orients the guard transverse to the neutral conductor. The clamp is stabilized by a mass located a predetermined distance below the neutral conductor, the mass acting as a pendulum to minimize rotation and oscillation of the guard. The mass may be a separate member distinct from the guard, or the guard itself can serve as the mass by suspending the guard below the neutral conductor using an elongated clamp. Further stabilization can be achieved in systems in which a consumer distribution line, e.g., a 120 VAC line, is located below the neutral conductor by providing an extension member attached to the clamp and extending vertically downward to the consumer line. The extension member is provided with a bifurcated end for receiving the consumer line so that rotation of the guard about the neutral conductor is opposed by reaction of the extension member against the consumer power line.